Related papers: The Hipparcos parallax for Polaris
We review five independent techniques which are used to set the distance scale to globular clusters, including subdwarf main sequence fitting utilizing the recent Hipparcos parallax catalogue. These data together all indicate that globular…
We report spectroscopic observations of the star HIP 50796, previously considered (but later rejected) as a candidate member of the TW Hya association. Our measurements reveal it to be a single-lined binary with an orbital period of 570…
Using the method of ``reduced parallaxes'' for the Halo RR Lyrae stars in the Hipparcos catalogue we derive a zero point of 0.77 $\pm$ 0.26 mag for an assumed slope of 0.18 in the $M_{\rm V}$-[Fe/H] relation. This is 0.28 magnitude brighter…
The 30 year orbit of the Cepheid Polaris has been followed with observations by the CHARA Array (Center for High Angular Resolution Astronomy) from 2016 through 2021. An additional measurement has been made with speckle interferometry at…
For more than 5000 stars with accurate parallaxes from the Hipparcos and Gaia DR1 Tycho-Gaia astrometric solution (TGAS), Tycho-2 photometry, interstellar polarization from eight catalogues and interstellar extinction from eight 3D maps the…
A previously-derived photometric parallax of 10.10+-0.20 mas, d=99+-2 pc, is confirmed for Polaris by a spectroscopic parallax derived using line ratios in high dispersion spectra for the Cepheid. The resulting estimates for the mean…
A globular cluster distance scale based on Hipparcos parallaxes of subdwarfs has been used to derive estimates of M_K for cluster Miras, including one in the SMC globular cluster NGC121. These lead to a zero-point of the Mira infrared…
The question of annual stellar parallax is usually viewed as having been a "win-win situation" for seventeenth-century astronomers who subscribed to the Copernican view of universe in which the Earth orbits the Sun and the Sun is one of…
It is argued that some of the recent claims for cosmology are grossly overblown. Cosmology rests on a very small database: it suffers from many fundamental difficulties as a science (if it is a science at all) whilst observations of distant…
Radial motions of stars in nearby moving clusters are determined from accurate proper motions and trigonometric parallaxes, without any use of spectroscopy. Assuming that cluster members share the same velocity vector (apart from a random…
Polaris the Cepheid has been observed for centuries, presenting surprises and changing our view of Cepheids and stellar astrophysics, in general. Specifically, understanding Polaris helps anchor the Cepheid Leavitt law, but the distance…
Determination of absolute parallaxes by means of a scanning astrometric satellite such as Hipparcos or Gaia relies on the short-term stability of the so-called basic angle between the two viewing directions. Uncalibrated variations of the…
By relying on recently improved Hipparcos parallaxes for the Hyades, Pleiades and Ursa Major clusters we find that stellar models with updated physical inputs nicely reproduce the location in the color magnitude diagram of main sequence…
Three independent sets of stellar theoretical models are tested with well-detached systems of the Hyades open cluster: 51 Tau, V818 Tau, and $\theta^2$ Tau. The choice of these objects is discussed and a statistical method is described and…
We present parallax determinations for six white dwarf candidates in the Torino Observatory Parallax Program. The absolute parallaxes are found with precisions at the 2-3 milliarcsecond level. For WD 1126+185 we find a distance incompatible…
Prediction of solar cycle is an important goal of Solar Physics both because it serves as a touchstone for our understanding of the sun and also because of its societal value for a space faring civilization. The task is difficult and…
Polaris is one of the most observed stars in the night sky, with recorded observations spanning more than 200 years. From these observations, one can study the real-time evolution of Polaris via the secular rate of change of the pulsation…
The present determination of the absolute magnitude $M_V(RR)$ of RR Lyrae stars is twofold, relying upon Hipparcos proper motions and trigonometric parallaxes separately. First, applying the statistical parallax method to the proper…
The timing and duration of exoplanet transits has a dependency on observer position due to parallax. In the case of an Earth-bound observer with a 2 AU baseline the dependency is typically small and slightly beyond the limits of current…
We present 33 new mid-eclipse times spanning approximately eight years of the eclipsing polar UZ Fornacis. We have used our new observations to test the two-planet model previously proposed to explain the variations in its eclipse times…